1. Field of the Invention
The invention relates to a light emitting diode (LED) lamp tube, more particularly to a lamp tube capable of providing uniform illumination and preventing glare.
2. Description of the Related Art
Conventional light emitting diode (LED) lamp tubes have a longer service life than fluorescent lamps and can replace the fluorescent lamps. Referring to FIG. 1, a conventional LED lamp tube 1 comprises a lamp device 11 and a tubular enclosure 12. The lamp device 11 includes a circuit board 111 disposed in the enclosure 12, a plurality of LEDs 112 electrically connected to the circuit board 111, and two electrode seats 113 electrically connected to the LEDs 112. The circuit board 111 divides an inner surface of the tubular enclosure 12 into a light-receiving portion and a non-illuminated portion.
However, the conventional LED lamp tubes encounter a problem during use in that glare is generated that can irritate users' eyes and make the users uncomfortable and dizzy due to the fact that the number of beams of light passing through the light-receiving portion of the tubular enclosure 12 reduces gradually from a middle portion of the light-receiving portion to junctions between the light-receiving portion and the non-illuminated portion. In particular, as illustrated in FIG. 2, with respect to an axial position of the lamp tube 1, the brightness of regions (b) is greater than that of each region (a), and smaller than that of region (c). As such, the brightness of the light-receiving portion of the tubular enclosure 12 is not uniform, and glare is generated.
In order to alleviate the above drawbacks, Taiwanese Patent Publication No. 330422 discloses an improved LED lamp tube. Referring to FIG. 3, the main difference between the improved LED lamp tube and the previously described LED lamp tube 1 resides in the configuration of the tubular enclosure. In the improved LED lamp tube, a plurality of transparent protrusions 121 are formed on an inner peripheral surface of the enclosure 12. Light emitted by the LEDs 112 is refracted in the protrusions 121 to redirect the light, thus reducing glare. However, the improved LED lamp tube cannot increase effectively uniformity of illumination. That is, the LED lamp is brighter at a middle portion of the light-receiving portion of the lamp tube, and darker at junctions of the light-receiving portion and the non-illuminated portion.